Pension and Postretirement Benefit Plans - Future Benefit Payments (Details) - Funded $ in Millions	Dec. 31, 2017 USD ($)
Qualified and Non-qualified Pension Benefits \| United States
Future Pension and Postretirement Benefit Payments
2018 Benefit Payments	$ 1,074
2019 Benefit Payments	1,090
2020 Benefit Payments	1,102
2021 Benefit Payments	1,110
2022 Benefit Payments	1,126
Next five years	5,724
Qualified and Non-qualified Pension Benefits \| International
Future Pension and Postretirement Benefit Payments
2018 Benefit Payments	237
2019 Benefit Payments	251
2020 Benefit Payments	260
2021 Benefit Payments	278
2022 Benefit Payments	285
Next five years	1,640
Postretirement Benefits
Future Pension and Postretirement Benefit Payments
2018 Benefit Payments	139
2019 Benefit Payments	148
2020 Benefit Payments	157
2021 Benefit Payments	166
2022 Benefit Payments	174
Next five years	$ 843

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- Definition

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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